git-rev-parse(1) - phpMan

GIT-REV-PARSE(1)                  Git Manual                  GIT-REV-PARSE(1)
NAME
       git-rev-parse - Pick out and massage parameters
SYNOPSIS
       git rev-parse [<options>] <args>...
DESCRIPTION
       Many Git porcelainish commands take a mixture of flags (i.e. parameters
       that begin with a dash -) and parameters meant for the underlying git
       rev-list command they use internally and flags and parameters for the
       other commands they use downstream of git rev-list. This command is
       used to distinguish between them.
OPTIONS
   Operation Modes
       Each of these options must appear first on the command line.
       --parseopt
           Use git rev-parse in option parsing mode (see PARSEOPT section
           below).
       --sq-quote
           Use git rev-parse in shell quoting mode (see SQ-QUOTE section
           below). In contrast to the --sq option below, this mode only does
           quoting. Nothing else is done to command input.
   Options for --parseopt
       --keep-dashdash
           Only meaningful in --parseopt mode. Tells the option parser to echo
           out the first -- met instead of skipping it.
       --stop-at-non-option
           Only meaningful in --parseopt mode. Lets the option parser stop at
           the first non-option argument. This can be used to parse
           sub-commands that take options themselves.
       --stuck-long
           Only meaningful in --parseopt mode. Output the options in their
           long form if available, and with their arguments stuck.
   Options for Filtering
       --revs-only
           Do not output flags and parameters not meant for git rev-list
           command.
       --no-revs
           Do not output flags and parameters meant for git rev-list command.
       --flags
           Do not output non-flag parameters.
       --no-flags
           Do not output flag parameters.
   Options for Output
       --default <arg>
           If there is no parameter given by the user, use <arg> instead.
       --prefix <arg>
           Behave as if git rev-parse was invoked from the <arg> subdirectory
           of the working tree. Any relative filenames are resolved as if they
           are prefixed by <arg> and will be printed in that form.
           This can be used to convert arguments to a command run in a
           subdirectory so that they can still be used after moving to the
           top-level of the repository. For example:
               prefix=$(git rev-parse --show-prefix)
               cd "$(git rev-parse --show-toplevel)"
               # rev-parse provides the -- needed for 'set'
               eval "set $(git rev-parse --sq --prefix "$prefix" -- "$@")"
       --verify
           Verify that exactly one parameter is provided, and that it can be
           turned into a raw 20-byte SHA-1 that can be used to access the
           object database. If so, emit it to the standard output; otherwise,
           error out.
           If you want to make sure that the output actually names an object
           in your object database and/or can be used as a specific type of
           object you require, you can add the ^{type} peeling operator to the
           parameter. For example, git rev-parse "$VAR^{commit}" will make
           sure $VAR names an existing object that is a commit-ish (i.e. a
           commit, or an annotated tag that points at a commit). To make sure
           that $VAR names an existing object of any type, git rev-parse
           "$VAR^{object}" can be used.
           Note that if you are verifying a name from an untrusted source, it
           is wise to use --end-of-options so that the name argument is not
           mistaken for another option.
       -q, --quiet
           Only meaningful in --verify mode. Do not output an error message if
           the first argument is not a valid object name; instead exit with
           non-zero status silently. SHA-1s for valid object names are printed
           to stdout on success.
       --sq
           Usually the output is made one line per flag and parameter. This
           option makes output a single line, properly quoted for consumption
           by shell. Useful when you expect your parameter to contain
           whitespaces and newlines (e.g. when using pickaxe -S with git
           diff-*). In contrast to the --sq-quote option, the command input is
           still interpreted as usual.
       --short[=length]
           Same as --verify but shortens the object name to a unique prefix
           with at least length characters. The minimum length is 4, the
           default is the effective value of the core.abbrev configuration
           variable (see git-config(1)).
       --not
           When showing object names, prefix them with ^ and strip ^ prefix
           from the object names that already have one.
       --abbrev-ref[=(strict|loose)]
           A non-ambiguous short name of the objects name. The option
           core.warnAmbiguousRefs is used to select the strict abbreviation
           mode.
       --symbolic
           Usually the object names are output in SHA-1 form (with possible ^
           prefix); this option makes them output in a form as close to the
           original input as possible.
       --symbolic-full-name
           This is similar to --symbolic, but it omits input that are not refs
           (i.e. branch or tag names; or more explicitly disambiguating
           "heads/master" form, when you want to name the "master" branch when
           there is an unfortunately named tag "master"), and shows them as
           full refnames (e.g. "refs/heads/master").
   Options for Objects
       --all
           Show all refs found in refs/.
       --branches[=pattern], --tags[=pattern], --remotes[=pattern]
           Show all branches, tags, or remote-tracking branches, respectively
           (i.e., refs found in refs/heads, refs/tags, or refs/remotes,
           respectively).
           If a pattern is given, only refs matching the given shell glob are
           shown. If the pattern does not contain a globbing character (?, *,
           or [), it is turned into a prefix match by appending /*.
       --glob=pattern
           Show all refs matching the shell glob pattern pattern. If the
           pattern does not start with refs/, this is automatically prepended.
           If the pattern does not contain a globbing character (?, *, or [),
           it is turned into a prefix match by appending /*.
       --exclude=<glob-pattern>
           Do not include refs matching <glob-pattern> that the next --all,
           --branches, --tags, --remotes, or --glob would otherwise consider.
           Repetitions of this option accumulate exclusion patterns up to the
           next --all, --branches, --tags, --remotes, or --glob option (other
           options or arguments do not clear accumulated patterns).
           The patterns given should not begin with refs/heads, refs/tags, or
           refs/remotes when applied to --branches, --tags, or --remotes,
           respectively, and they must begin with refs/ when applied to --glob
           or --all. If a trailing /* is intended, it must be given
           explicitly.
       --exclude-hidden=[fetch|receive|uploadpack]
           Do not include refs that would be hidden by git-fetch,
           git-receive-pack or git-upload-pack by consulting the appropriate
           fetch.hideRefs, receive.hideRefs or uploadpack.hideRefs
           configuration along with transfer.hideRefs (see git-config(1)).
           This option affects the next pseudo-ref option --all or --glob and
           is cleared after processing them.
       --disambiguate=<prefix>
           Show every object whose name begins with the given prefix. The
           <prefix> must be at least 4 hexadecimal digits long to avoid
           listing each and every object in the repository by mistake.
   Options for Files
       --local-env-vars
           List the GIT_* environment variables that are local to the
           repository (e.g. GIT_DIR or GIT_WORK_TREE, but not GIT_EDITOR).
           Only the names of the variables are listed, not their value, even
           if they are set.
       --path-format=(absolute|relative)
           Controls the behavior of certain other options. If specified as
           absolute, the paths printed by those options will be absolute and
           canonical. If specified as relative, the paths will be relative to
           the current working directory if that is possible. The default is
           option specific.
           This option may be specified multiple times and affects only the
           arguments that follow it on the command line, either to the end of
           the command line or the next instance of this option.
       The following options are modified by --path-format:
       --git-dir
           Show $GIT_DIR if defined. Otherwise show the path to the .git
           directory. The path shown, when relative, is relative to the
           current working directory.
           If $GIT_DIR is not defined and the current directory is not
           detected to lie in a Git repository or work tree print a message to
           stderr and exit with nonzero status.
       --git-common-dir
           Show $GIT_COMMON_DIR if defined, else $GIT_DIR.
       --resolve-git-dir <path>
           Check if <path> is a valid repository or a gitfile that points at a
           valid repository, and print the location of the repository. If
           <path> is a gitfile then the resolved path to the real repository
           is printed.
       --git-path <path>
           Resolve "$GIT_DIR/<path>" and takes other path relocation variables
           such as $GIT_OBJECT_DIRECTORY, $GIT_INDEX_FILE... into account. For
           example, if $GIT_OBJECT_DIRECTORY is set to /foo/bar then "git
           rev-parse --git-path objects/abc" returns /foo/bar/abc.
       --show-toplevel
           Show the (by default, absolute) path of the top-level directory of
           the working tree. If there is no working tree, report an error.
       --show-superproject-working-tree
           Show the absolute path of the root of the superproject's working
           tree (if exists) that uses the current repository as its submodule.
           Outputs nothing if the current repository is not used as a
           submodule by any project.
       --shared-index-path
           Show the path to the shared index file in split index mode, or
           empty if not in split-index mode.
       The following options are unaffected by --path-format:
       --absolute-git-dir
           Like --git-dir, but its output is always the canonicalized absolute
           path.
       --is-inside-git-dir
           When the current working directory is below the repository
           directory print "true", otherwise "false".
       --is-inside-work-tree
           When the current working directory is inside the work tree of the
           repository print "true", otherwise "false".
       --is-bare-repository
           When the repository is bare print "true", otherwise "false".
       --is-shallow-repository
           When the repository is shallow print "true", otherwise "false".
       --show-cdup
           When the command is invoked from a subdirectory, show the path of
           the top-level directory relative to the current directory
           (typically a sequence of "../", or an empty string).
       --show-prefix
           When the command is invoked from a subdirectory, show the path of
           the current directory relative to the top-level directory.
       --show-object-format[=(storage|input|output)]
           Show the object format (hash algorithm) used for the repository for
           storage inside the .git directory, input, or output. For input,
           multiple algorithms may be printed, space-separated. If not
           specified, the default is "storage".
   Other Options
       --since=datestring, --after=datestring
           Parse the date string, and output the corresponding --max-age=
           parameter for git rev-list.
       --until=datestring, --before=datestring
           Parse the date string, and output the corresponding --min-age=
           parameter for git rev-list.
       <args>...
           Flags and parameters to be parsed.
SPECIFYING REVISIONS
       A revision parameter <rev> typically, but not necessarily, names a
       commit object. It uses what is called an extended SHA-1 syntax. Here
       are various ways to spell object names. The ones listed near the end of
       this list name trees and blobs contained in a commit.
           Note
           This document shows the "raw" syntax as seen by git. The shell and
           other UIs might require additional quoting to protect special
           characters and to avoid word splitting.
       <sha1>, e.g. dae86e1950b1277e545cee180551750029cfe735, dae86e
           The full SHA-1 object name (40-byte hexadecimal string), or a
           leading substring that is unique within the repository. E.g.
           dae86e1950b1277e545cee180551750029cfe735 and dae86e both name the
           same commit object if there is no other object in your repository
           whose object name starts with dae86e.
       <describeOutput>, e.g. v1.7.4.2-679-g3bee7fb
           Output from git describe; i.e. a closest tag, optionally followed
           by a dash and a number of commits, followed by a dash, a g, and an
           abbreviated object name.
       <refname>, e.g. master, heads/master, refs/heads/master
           A symbolic ref name. E.g.  master typically means the commit object
           referenced by refs/heads/master. If you happen to have both
           heads/master and tags/master, you can explicitly say heads/master
           to tell Git which one you mean. When ambiguous, a <refname> is
           disambiguated by taking the first match in the following rules:
            1. If $GIT_DIR/<refname> exists, that is what you mean (this is
               usually useful only for HEAD, FETCH_HEAD, ORIG_HEAD,
               MERGE_HEAD, REBASE_HEAD, REVERT_HEAD, CHERRY_PICK_HEAD,
               BISECT_HEAD and AUTO_MERGE);
            2. otherwise, refs/<refname> if it exists;
            3. otherwise, refs/tags/<refname> if it exists;
            4. otherwise, refs/heads/<refname> if it exists;
            5. otherwise, refs/remotes/<refname> if it exists;
            6. otherwise, refs/remotes/<refname>/HEAD if it exists.
           HEAD
               names the commit on which you based the changes in the working
               tree.
           FETCH_HEAD
               records the branch which you fetched from a remote repository
               with your last git fetch invocation.
           ORIG_HEAD
               is created by commands that move your HEAD in a drastic way
               (git am, git merge, git rebase, git reset), to record the
               position of the HEAD before their operation, so that you can
               easily change the tip of the branch back to the state before
               you ran them.
           MERGE_HEAD
               records the commit(s) which you are merging into your branch
               when you run git merge.
           REBASE_HEAD
               during a rebase, records the commit at which the operation is
               currently stopped, either because of conflicts or an edit
               command in an interactive rebase.
           REVERT_HEAD
               records the commit which you are reverting when you run git
               revert.
           CHERRY_PICK_HEAD
               records the commit which you are cherry-picking when you run
               git cherry-pick.
           BISECT_HEAD
               records the current commit to be tested when you run git bisect
               --no-checkout.
           AUTO_MERGE
               records a tree object corresponding to the state the ort merge
               strategy wrote to the working tree when a merge operation
               resulted in conflicts.
           Note that any of the refs/* cases above may come either from the
           $GIT_DIR/refs directory or from the $GIT_DIR/packed-refs file.
           While the ref name encoding is unspecified, UTF-8 is preferred as
           some output processing may assume ref names in UTF-8.
       @
           @ alone is a shortcut for HEAD.
       [<refname>]@{<date>}, e.g. master@{yesterday}, HEAD@{5 minutes ago}
           A ref followed by the suffix @ with a date specification enclosed
           in a brace pair (e.g.  {yesterday}, {1 month 2 weeks 3 days 1 hour
           1 second ago} or {1979-02-26 18:30:00}) specifies the value of the
           ref at a prior point in time. This suffix may only be used
           immediately following a ref name and the ref must have an existing
           log ($GIT_DIR/logs/<ref>). Note that this looks up the state of
           your local ref at a given time; e.g., what was in your local master
           branch last week. If you want to look at commits made during
           certain times, see --since and --until.
       <refname>@{<n>}, e.g. master@{1}
           A ref followed by the suffix @ with an ordinal specification
           enclosed in a brace pair (e.g.  {1}, {15}) specifies the n-th prior
           value of that ref. For example master@{1} is the immediate prior
           value of master while master@{5} is the 5th prior value of master.
           This suffix may only be used immediately following a ref name and
           the ref must have an existing log ($GIT_DIR/logs/<refname>).
       @{<n>}, e.g. @{1}
           You can use the @ construct with an empty ref part to get at a
           reflog entry of the current branch. For example, if you are on
           branch blabla then @{1} means the same as blabla@{1}.
       @{-<n>}, e.g. @{-1}
           The construct @{-<n>} means the <n>th branch/commit checked out
           before the current one.
       [<branchname>]@{upstream}, e.g. master@{upstream}, @{u}
           A branch B may be set up to build on top of a branch X (configured
           with branch.<name>.merge) at a remote R (configured with the branch
           X taken from remote R, typically found at refs/remotes/R/X.
       [<branchname>]@{push}, e.g. master@{push}, @{push}
           The suffix @{push} reports the branch "where we would push to" if
           git push were run while branchname was checked out (or the current
           HEAD if no branchname is specified). Like for @{upstream}, we
           report the remote-tracking branch that corresponds to that branch
           at the remote.
           Here's an example to make it more clear:
               $ git config push.default current
               $ git config remote.pushdefault myfork
               $ git switch -c mybranch origin/master
               $ git rev-parse --symbolic-full-name @{upstream}
               refs/remotes/origin/master
               $ git rev-parse --symbolic-full-name @{push}
               refs/remotes/myfork/mybranch
           Note in the example that we set up a triangular workflow, where we
           pull from one location and push to another. In a non-triangular
           workflow, @{push} is the same as @{upstream}, and there is no need
           for it.
           This suffix is also accepted when spelled in uppercase, and means
           the same thing no matter the case.
       <rev>^[<n>], e.g. HEAD^, v1.5.1^0
           A suffix ^ to a revision parameter means the first parent of that
           commit object.  ^<n> means the <n>th parent (i.e.  <rev>^ is
           equivalent to <rev>^1). As a special rule, <rev>^0 means the commit
           itself and is used when <rev> is the object name of a tag object
           that refers to a commit object.
       <rev>~[<n>], e.g. HEAD~, master~3
           A suffix ~ to a revision parameter means the first parent of that
           commit object. A suffix ~<n> to a revision parameter means the
           commit object that is the <n>th generation ancestor of the named
           commit object, following only the first parents. I.e.  <rev>~3 is
           equivalent to <rev>^^^ which is equivalent to <rev>^1^1^1. See
           below for an illustration of the usage of this form.
       <rev>^{<type>}, e.g. v0.99.8^{commit}
           A suffix ^ followed by an object type name enclosed in brace pair
           means dereference the object at <rev> recursively until an object
           of type <type> is found or the object cannot be dereferenced
           anymore (in which case, barf). For example, if <rev> is a
           commit-ish, <rev>^{commit} describes the corresponding commit
           object. Similarly, if <rev> is a tree-ish, <rev>^{tree} describes
           the corresponding tree object.  <rev>^0 is a short-hand for
           <rev>^{commit}.
           <rev>^{object} can be used to make sure <rev> names an object that
           exists, without requiring <rev> to be a tag, and without
           dereferencing <rev>; because a tag is already an object, it does
           not have to be dereferenced even once to get to an object.
           <rev>^{tag} can be used to ensure that <rev> identifies an existing
           tag object.
       <rev>^{}, e.g. v0.99.8^{}
           A suffix ^ followed by an empty brace pair means the object could
           be a tag, and dereference the tag recursively until a non-tag
           object is found.
       <rev>^{/<text>}, e.g. HEAD^{/fix nasty bug}
           A suffix ^ to a revision parameter, followed by a brace pair that
           contains a text led by a slash, is the same as the :/fix nasty bug
           syntax below except that it returns the youngest matching commit
           which is reachable from the <rev> before ^.
       :/<text>, e.g. :/fix nasty bug
           A colon, followed by a slash, followed by a text, names a commit
           whose commit message matches the specified regular expression. This
           name returns the youngest matching commit which is reachable from
           any ref, including HEAD. The regular expression can match any part
           of the commit message. To match messages starting with a string,
           one can use e.g.  :/^foo. The special sequence :/!  is reserved for
           modifiers to what is matched.  :/!-foo performs a negative match,
           while :/!!foo matches a literal !  character, followed by foo. Any
           other sequence beginning with :/!  is reserved for now. Depending
           on the given text, the shell's word splitting rules might require
           additional quoting.
       <rev>:<path>, e.g. HEAD:README, master:./README
           A suffix : followed by a path names the blob or tree at the given
           path in the tree-ish object named by the part before the colon. A
           path starting with ./ or ../ is relative to the current working
           directory. The given path will be converted to be relative to the
           working tree's root directory. This is most useful to address a
           blob or tree from a commit or tree that has the same tree structure
           as the working tree.
       :[<n>:]<path>, e.g. :0:README, :README
           A colon, optionally followed by a stage number (0 to 3) and a
           colon, followed by a path, names a blob object in the index at the
           given path. A missing stage number (and the colon that follows it)
           names a stage 0 entry. During a merge, stage 1 is the common
           ancestor, stage 2 is the target branch's version (typically the
           current branch), and stage 3 is the version from the branch which
           is being merged.
       Here is an illustration, by Jon Loeliger. Both commit nodes B and C are
       parents of commit node A. Parent commits are ordered left-to-right.
           G   H   I   J
            \ /     \ /
             D   E   F
              \  |  / \
               \ | /   |
                \|/    |
                 B     C
                  \   /
                   \ /
                    A
           A =      = A^0
           B = A^   = A^1     = A~1
           C =      = A^2
           D = A^^  = A^1^1   = A~2
           E = B^2  = A^^2
           F = B^3  = A^^3
           G = A^^^ = A^1^1^1 = A~3
           H = D^2  = B^^2    = A^^^2  = A~2^2
           I = F^   = B^3^    = A^^3^
           J = F^2  = B^3^2   = A^^3^2
SPECIFYING RANGES
       History traversing commands such as git log operate on a set of
       commits, not just a single commit.
       For these commands, specifying a single revision, using the notation
       described in the previous section, means the set of commits reachable
       from the given commit.
       Specifying several revisions means the set of commits reachable from
       any of the given commits.
       A commit's reachable set is the commit itself and the commits in its
       ancestry chain.
       There are several notations to specify a set of connected commits
       (called a "revision range"), illustrated below.
   Commit Exclusions
       ^<rev> (caret) Notation
           To exclude commits reachable from a commit, a prefix ^ notation is
           used. E.g.  ^r1 r2 means commits reachable from r2 but exclude the
           ones reachable from r1 (i.e.  r1 and its ancestors).
   Dotted Range Notations
       The .. (two-dot) Range Notation
           The ^r1 r2 set operation appears so often that there is a shorthand
           for it. When you have two commits r1 and r2 (named according to the
           syntax explained in SPECIFYING REVISIONS above), you can ask for
           commits that are reachable from r2 excluding those that are
           reachable from r1 by ^r1 r2 and it can be written as r1..r2.
       The ... (three-dot) Symmetric Difference Notation
           A similar notation r1...r2 is called symmetric difference of r1 and
           r2 and is defined as r1 r2 --not $(git merge-base --all r1 r2). It
           is the set of commits that are reachable from either one of r1
           (left side) or r2 (right side) but not from both.
       In these two shorthand notations, you can omit one end and let it
       default to HEAD. For example, origin.. is a shorthand for origin..HEAD
       and asks "What did I do since I forked from the origin branch?"
       Similarly, ..origin is a shorthand for HEAD..origin and asks "What did
       the origin do since I forked from them?" Note that .. would mean
       HEAD..HEAD which is an empty range that is both reachable and
       unreachable from HEAD.
       Commands that are specifically designed to take two distinct ranges
       (e.g. "git range-diff R1 R2" to compare two ranges) do exist, but they
       are exceptions. Unless otherwise noted, all "git" commands that operate
       on a set of commits work on a single revision range. In other words,
       writing two "two-dot range notation" next to each other, e.g.
           $ git log A..B C..D
       does not specify two revision ranges for most commands. Instead it will
       name a single connected set of commits, i.e. those that are reachable
       from either B or D but are reachable from neither A or C. In a linear
       history like this:
           ---A---B---o---o---C---D
       because A and B are reachable from C, the revision range specified by
       these two dotted ranges is a single commit D.
   Other <rev>^ Parent Shorthand Notations
       Three other shorthands exist, particularly useful for merge commits,
       for naming a set that is formed by a commit and its parent commits.
       The r1^@ notation means all parents of r1.
       The r1^! notation includes commit r1 but excludes all of its parents.
       By itself, this notation denotes the single commit r1.
       The <rev>^-[<n>] notation includes <rev> but excludes the <n>th parent
       (i.e. a shorthand for <rev>^<n>..<rev>), with <n> = 1 if not given.
       This is typically useful for merge commits where you can just pass
       <commit>^- to get all the commits in the branch that was merged in
       merge commit <commit> (including <commit> itself).
       While <rev>^<n> was about specifying a single commit parent, these
       three notations also consider its parents. For example you can say
       HEAD^2^@, however you cannot say HEAD^@^2.
REVISION RANGE SUMMARY
       <rev>
           Include commits that are reachable from <rev> (i.e. <rev> and its
           ancestors).
       ^<rev>
           Exclude commits that are reachable from <rev> (i.e. <rev> and its
           ancestors).
       <rev1>..<rev2>
           Include commits that are reachable from <rev2> but exclude those
           that are reachable from <rev1>. When either <rev1> or <rev2> is
           omitted, it defaults to HEAD.
       <rev1>...<rev2>
           Include commits that are reachable from either <rev1> or <rev2> but
           exclude those that are reachable from both. When either <rev1> or
           <rev2> is omitted, it defaults to HEAD.
       <rev>^@, e.g. HEAD^@
           A suffix ^ followed by an at sign is the same as listing all
           parents of <rev> (meaning, include anything reachable from its
           parents, but not the commit itself).
       <rev>^!, e.g. HEAD^!
           A suffix ^ followed by an exclamation mark is the same as giving
           commit <rev> and all its parents prefixed with ^ to exclude them
           (and their ancestors).
       <rev>^-<n>, e.g. HEAD^-, HEAD^-2
           Equivalent to <rev>^<n>..<rev>, with <n> = 1 if not given.
       Here are a handful of examples using the Loeliger illustration above,
       with each step in the notation's expansion and selection carefully
       spelt out:
              Args   Expanded arguments    Selected commits
              D                            G H D
              D F                          G H I J D F
              ^G D                         H D
              ^D B                         E I J F B
              ^D B C                       E I J F B C
              C                            I J F C
              B..C   = ^B C                C
              B...C  = B ^F C              G H D E B C
              B^-    = B^..B
                     = ^B^1 B              E I J F B
              C^@    = C^1
                     = F                   I J F
              B^@    = B^1 B^2 B^3
                     = D E F               D G H E F I J
              C^!    = C ^C^@
                     = C ^C^1
                     = C ^F                C
              B^!    = B ^B^@
                     = B ^B^1 ^B^2 ^B^3
                     = B ^D ^E ^F          B
              F^! D  = F ^I ^J D           G H D F
PARSEOPT
       In --parseopt mode, git rev-parse helps massaging options to bring to
       shell scripts the same facilities C builtins have. It works as an
       option normalizer (e.g. splits single switches aggregate values), a bit
       like getopt(1) does.
       It takes on the standard input the specification of the options to
       parse and understand, and echoes on the standard output a string
       suitable for sh(1) eval to replace the arguments with normalized ones.
       In case of error, it outputs usage on the standard error stream, and
       exits with code 129.
       Note: Make sure you quote the result when passing it to eval. See below
       for an example.
   Input Format
       git rev-parse --parseopt input format is fully text based. It has two
       parts, separated by a line that contains only --. The lines before the
       separator (should be one or more) are used for the usage. The lines
       after the separator describe the options.
       Each line of options has this format:
           <opt-spec><flags>*<arg-hint>? SP+ help LF
       <opt-spec>
           its format is the short option character, then the long option name
           separated by a comma. Both parts are not required, though at least
           one is necessary. May not contain any of the <flags> characters.
           h,help, dry-run and f are examples of correct <opt-spec>.
       <flags>
           <flags> are of *, =, ?  or !.
           o   Use = if the option takes an argument.
           o   Use ?  to mean that the option takes an optional argument. You
               probably want to use the --stuck-long mode to be able to
               unambiguously parse the optional argument.
           o   Use * to mean that this option should not be listed in the
               usage generated for the -h argument. It's shown for --help-all
               as documented in gitcli(7).
           o   Use !  to not make the corresponding negated long option
               available.
       <arg-hint>
           <arg-hint>, if specified, is used as a name of the argument in the
           help output, for options that take arguments.  <arg-hint> is
           terminated by the first whitespace. It is customary to use a dash
           to separate words in a multi-word argument hint.
       The remainder of the line, after stripping the spaces, is used as the
       help associated with the option.
       Blank lines are ignored, and lines that don't match this specification
       are used as option group headers (start the line with a space to create
       such lines on purpose).
   Example
           OPTS_SPEC="\
           some-command [<options>] <args>...
           some-command does foo and bar!
           --
           h,help!   show the help
           foo       some nifty option --foo
           bar=      some cool option --bar with an argument
           baz=arg   another cool option --baz with a named argument
           qux?path  qux may take a path argument but has meaning by itself
             An option group Header
           C?        option C with an optional argument"
           eval "$(echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?)"
   Usage text
       When "$@" is -h or --help in the above example, the following usage
       text would be shown:
           usage: some-command [<options>] <args>...
               some-command does foo and bar!
               -h, --help            show the help
               --[no-]foo            some nifty option --foo
               --[no-]bar ...        some cool option --bar with an argument
               --[no-]baz <arg>      another cool option --baz with a named argument
               --[no-]qux[=<path>]   qux may take a path argument but has meaning by itself
           An option group Header
               -C[...]               option C with an optional argument
SQ-QUOTE
       In --sq-quote mode, git rev-parse echoes on the standard output a
       single line suitable for sh(1) eval. This line is made by normalizing
       the arguments following --sq-quote. Nothing other than quoting the
       arguments is done.
       If you want command input to still be interpreted as usual by git
       rev-parse before the output is shell quoted, see the --sq option.
   Example
           $ cat >your-git-script.sh <<\EOF
           #!/bin/sh
           args=$(git rev-parse --sq-quote "$@")   # quote user-supplied arguments
           command="git frotz -n24 $args"          # and use it inside a handcrafted
                                                   # command line
           eval "$command"
           EOF
           $ sh your-git-script.sh "a b'c"
EXAMPLES
       o   Print the object name of the current commit:
               $ git rev-parse --verify HEAD
       o   Print the commit object name from the revision in the $REV shell
           variable:
               $ git rev-parse --verify --end-of-options $REV^{commit}
           This will error out if $REV is empty or not a valid revision.
       o   Similar to above:
               $ git rev-parse --default master --verify --end-of-options $REV
           but if $REV is empty, the commit object name from master will be
           printed.
GIT
       Part of the git(1) suite
Git 2.43.5                        05/31/2024                  GIT-REV-PARSE(1)